Voltage regulator



w. w. JOHNSTON ET Al. 2,373,119

April 1d, 17945.

VOLTAGE REGULATOR l Filed April 10, 1945 I INVENTORS mar-Ld. PLI-Im WE Patented Apr. 10, 1945 OFFICE VOLTAGE REGULATOR Walter W. Johnston and Raymond H. Howe,

United States Navy Application April 10, 1943, Serial No. 482,588

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 5 Claims.

Our invention relates in general to voltage regulators for generators and in particular t such regulators which incorporate a variable resistor connected in series with the generator seid winding, the resistor being controlled by means of a. contact arm connected to the movable core of a solenoid energized by the terminal voltage of the generator.

`litegulators of this particular type comprising a solenoid operated rheostat are well known but it is believed that the improved construction offered by' the present application constitutes a meritorious advance in the art.

The general object of our invention therefore is to provide an improved voltage regulator of the class described which will maintain the terminal voltage of a generator at a constant value.

I"A more specific object is to provide novel means for adjusting the connections between the reciprocally movable core of the solenoid and the pivotally movably contact arm of the rheostat so that the amount of resistance cut into and out of the generator iield circuit per unit length of travel of the core may be varied to suit different conditions of calibration for the regulator.

These and other objects of our invention will become more apparent from the detailed description to follow and from the accompanying drawing, the single iigure of which is an elevational view of a preferred embodiment of the invention with the housing cover removed and certain parts shown in section. Electrical connections between the regulator and a shunt type generator are shown schematically.

Referring now to the drawing, a housing 2 for the regulator is shown with the cover removed. A solenoid 3 having a winding 4, a, winding support 5 and a soit iron core on plunger E is provided, the support 5 being Secured'by any suitable means to one Wall of housing 2. Resilient means consisting of a plurality of seriately connected button or disc type springs 'I are disposed within the central opening through the solenoid 3. This type of spring is preferred because it has a more linear pressure characteristic than a coil spring. The topmost spring bears against the bottom of the core 6 and a bearing plate 8 is provided on the base of the lowermost spring. An adjusting screw 9 having a knurled head I0 threads through a collar I I secured to the wall of the housing 2 and the end of the screw 9 bears against the underside of plate 8. Screw 9 may be locked in any position by means of a lock nut I2. The static or no-load voltage regulation is determined by the position of screw 9, which, acting through the springs 1, sets the average 0perating point for the apparatus.

A plurality of spaced pins I3 secured to, and upstanding from, one wall of housing 2 are provided to carry a plate member I4 which may be made of any suitable electrically insulating material. The pins I3 project through complementary spaced, elongated slots I5 provided in plate I4 and transverse movement of plate I4 is provided by a screw I B. Screw I6 having a knurled head I'I threads into a recess portion I8 provided in one end of plate I4. Thus as screw I6 is rotated (but'cannot move along its axis because of the retaining collars I9, 20), plate I4 will be moved transversely.

Mounted upon the plate I4 is a slide wire rheostat 2| consisting of a at wound curved Wire resistor 22 and a carbon brush 23, the latter being. carried in a recess 24 provided in an arm member 25 which is pivotally mounted on pin 26 upstanding from plate I4. The arm 25 is'also made of suitable electrically insulating material and a spring 2 is provided between one end of brush 23 and the bottom of recess 24 to urge brush 23 into good electrical contact with the resistor 22.

Arm 25 is provided with a transversely arranged slotted portion 28, and a pin 29 which passes through slo-t 28 and is secured to the top end of core B provides pivotal connecting means between core 6 and arm 25.

To connect the regulator in circuit, the resistor 22 is connected in series with the field winding 30 oi a. generator by conductors 3| and 32. Conductor 3| is connected between one side of the generator eld winding 30 and brush 23'while conductor 32 is connected between one side of the generator armature 33 and one Vend of the r'esistor 22.

Conductors 34 and 35 take power outwardly from the output terminals of the generator to supply its load and the solenoid winding 3 is connected by conductors 36 and 3'! so as to be energized by the terminal voltage of the generator.

By turning the screw I6, which moves plate I4 and hence arm 25 transversely; the distance between pivot pins 2S and 29 is varied, thus varying the ratio of movement of arm 25 to core B, and determining the amount of resistance which is added to or subtracted from the generator field circuit for a given displacement of the core 6.

Operation manner:

Assuming that for a given generator terminal voltage, the core 5 occupies the position shown in the drawing. Il the terminal voltage of the generator should new tend to decrease which tendency might be caused by an increase in output current, or decrease in eld strength or decrease in speed, the current ow through the coil will ldecrease and will likewise decrease the pull exerted thereby on core 6. As the pull on core 6 lessens, the restoring force in `springs regulator operates in the following 7 push core arm 25 and brush 23 upwardly thereby decreasing the amount of resistance in series with the generator eld winding 3B. This allows more current to iiow through the eld winding increasing the field uX and hence the voltage output of the genera-tor is also increased.

Conversely if the terminal voltage of the generator should for any reason tend to increase, current flow in coil 3 and the pull exerted on core 6 will likewise increase. This pulls core 6 further Within the core opening and thereby increases the resistance in series with the generator eld winding 3G. Current flow through winding 3D is thereby decreased which decreases the generator field flux and hence the terminal voitage of the generator is also decreased.

Thus it Will be evident that any tendency towards a decrease in terminal voltage of the generator will be oset by an increase in generated voltage while any tendency towards an increase in terminal voltage of the generator will be onset by a decrease in generated voltage. The net result of this is 'that substantially a constant terminal voltage on thel generator is maintained irrespective of any condition which might tend to change this voltage. i

In conclusion, We Wish it to be understood that the particular construction which has been described represents only one embodiment of the invention andthat various changes therein may occur to 'those skilled in the art Without departing from the spirit and scope ofthe invention as deiined in the appended claims.

For'example, it may be desirable, in some instances, to replace the curved resistor 22 with a plurality of arcuately arranged contact members which are wiped by the brush 23, resistance coils of any desired resistance values being connected between adjacent contact members so that as the brush 123 passes from one contact to another, the resistance coils are cut in and out of the iield circuit. Such a Contact arrangement per se is shownin U. S. Patent No. 589,073.

invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We'claim:

i. In a regulator for a generator a solenoid including a. movable core, a rlieostat comprising a movable contact arm and a resistor, said resistor being adapted to be connected in the eld circuit of said generator, means for connecting said movable core with said movable contact arm, and means for modifying said connecting means whereby changes in ratio of movement of said contact arm to movement of said core may be eiected.

2. In a regulator for a generator, a solenoid including a4 movable core, a rheostat comprising a contact arm and a resistor, said resistor-.being adapted to be connected in circuit relation with CIL the eld winding of said generator, rst pivot means about which said contact arm is movable to vary the resistance of said resistor, second pivot means connecting said core to said contact arm, and means for varying the distance between said rst and second pivot means to thereby vary the ratio of movement of said contact arm to movement of said core.

3. In a regulator for a generator, a, solenoid adapted to be energized by the voltage produced by said generator andincluding a movable core, a rheostat comprising a support plate, a curved resistor mounted on said support plate, an arm member having contact means at one end thereof to engage said resistor and rst pivot means at the opposite end thereof for pivotally mounting said arm member on said support plate, sec- 0nd pivot means connecting said core to said arm member intermediate said first pivot means and said Contact means, and means for moving said support plate and arm member carried thereby transversely of the axis of movement of said core to vary the distance between said first and second pivot means thereby varying the ratio of movement of said arm member to movement of said core.

4. In a regulator for a. generator, a solenoid including a movable core, a. rheostat adapted to be connected in the eld circuit of said generator, said rheostat including a support plate, a curved resistor disposed on said plate, a resistor contact arm having a slotted portion and first pivot pin means for pivotally mounting said contact arm on said support plate, said arm extending substantially normal to the axis ci movement of `said core, second pivot means comprising a pin secured to the end of said core and extending into the slotted portion of said contact arm for connecting said contact arm to said core, and means for moving said support plate, contact arm and resistor carried thereby relative to said core to eect a change in the distance between said rst and second pivot pin means and hence a change in the ratio of movement of said contact arm to movement of said core.

5. In a regulator for a generator, a. rheostat including an arm and resistor, said rheostat being adapted to be connected in circuit relation with the eld winding of said generator, a solenoid adapted to be electrically connected with the terminals and generator, said solenoid including a movable core, resilient means opposing movement ofsaid core, said resilient means comprising one or more ldisk type springs, first `pivot means about which said rheostat arm is movable to vary the resistance of said resistor, second pivot means connecting said core to said rheostat arm, and means for varying the distance between- 

